The present invention relates to door latches and especially to a door latch which allows a door to be partially opened while latched.
In the past a wide variety of door locks have been provided for various types of doors. A typical door lock has a locking cylinder mounted through a door which may be operated with a key for sliding a dead bolt or latching bolt from the door into a face plate mounted on the door jamb. This type of latch may also have a separate door knob or may have the cylinder mounted in the door knob. Other types of locks include mortise locks and various types of locks for sliding glass doors and windows. One common type of lock commonly found in motel and hotels is a chain lock door bolt which has a door plate which is attached with screws to the inside of the door. The door plate has a slot with an enlarged opening at one end while the jamb has a jamb plate attached thereto with screws, A chain is fixedly attached to the same plate. The chain has a slide bolt on one end which can be placed in the enlarged opening of the slot and slid into the slot of the door plate to allow the door to be partially opened while maintaining the door in a locked position. Typically this type of prior art chain lock has a retainer opening in the jamb plate for holding the slide bolt when the chain lock is disconnected. A second type of lock which works similar to a chain lock for allowing a door to be partially opened includes an arcuate hinged latching member shaped like an elongated "U" which allows a locking bolt to fit therein to allow the door to slide to the end of the elongated arcuate "U". The principal disadvantage of both of these prior art type chain locks is that the screws are generally mounted on the inside of the door and jamb so that the doors can be kicked open, breaking the jamb plate or the door plate away from the door jamb and allowing an intruder to enter through the door. The present invention is aimed at a more secure locking system for allowing the door to be partially open while remaining latched and which has a more aesthetic appearance.